[PATCH u-boot 2/2] Makefile: Build working u-boot-dtb.bin target also for mpc85xx

[Pali Rohár]

On Friday 30 December 2022 09:49:08 Simon Glass wrote:
> Hi Pali,
> 
> On Fri, 30 Dec 2022 at 09:44, Pali Rohár <pali at kernel.org> wrote:
> >
> > On Friday 30 December 2022 10:41:47 Tom Rini wrote:
> > > On Fri, Dec 30, 2022 at 04:24:43PM +0100, Pali Rohár wrote:
> > > > On Friday 30 December 2022 10:21:04 Tom Rini wrote:
> > > > > > In this case it would be better to build u-boot-dts.bin only by binman
> > > > > > (for all platforms) instead of cat-ing rules in Makefile.
> > > > >
> > > > > This would also be an easier path forward perhaps for making sure that
> > > > > the dtb is always 8 byte aligned?
> > > >
> > > > Well, no. With DTB the problem is that it is not put to the correct
> > > > offset as can be specified in linker script. So moving this code from
> > > > Makefile to binman also moves this problem to another location.
> > > > 8 byte alignment is just subset of the "correct offset" problem.
> > >
> > > Right, the high level answer is binman is intended to be the tool to
> > > assemble binaries, and has to deal with "make sure binary X is at offset
> > > Y, which also has a linker symbol for run-time references".
> >
> > Ok, if this tool has access to ELF/linker symbols (or will have in
> > future in case it does not have yet) then this problem could be solved
> > here.
> 
> It does have this access and already updates symbols in some cases.
> See [1].
> [1] https://u-boot.readthedocs.io/en/latest/develop/package/binman.html#access-to-binman-entry-offsets-at-run-time-symbols

I just do not see how to do it, but ok, maybe something more is needed.

> I am a little nervous about a complete move to binman in this
> area even for simple things like u-boot.bin, since it would set off
> yet another migration.

Yes, it sounds like a big change.

> But perhaps most boards don't actually use u-boot.bin anyway?

I think that most boards _use_ u-boot.bin. Or wrap u-boot.bin into some
own container (by mkimage).

> Part of me thinks we should solve this in the .lds files, since
> otherwise we are blurring the line between building and packaging.

Linker script files in any case would have to be adjusted / fixed to
align _end symbol. Without it ELF symbol would not be correct and so
obviously any solution depending on ELF symbols would not work...

As I wrote recently, I proposed alternative solution without binman:
https://lore.kernel.org/u-boot/20221217235913.w7ihsktbplbp2j7z@pali/

> Regards,
> SImon
>